Door operator

ABSTRACT

A door operator for a canopy-type door including a small driving pinion normally maintained in meshing engagement with an elongated rack member. The driving pinion is preferably rotatably mounted on the door and the elongated rack is preferably pivotally mounted on the adjacent door frame. Resilient means normally maintain the pinion and rack in meshing engagement whereby the driving pinion, being of small diameter, effective functions as a restraining device to hold the door in a stationary position. Manually releasable means are provided for permitting disengagement of the rack and driving pinion to permit manual operation of the door.

United States Patent 1,862,860 6/1932 Morse John R. Law

Fraser, Mich.

Mar. 10, 1969 July 13, 1971 Tilt-A-Door Corporation Detroit, Mich.

inventor Appl. No Filed Patented Assignee DOOR OPERATOR 12 Claims, 7 Drawing Figs.

References Cited UNITED STATES PATENTS Primary Examiner-J. Karl Bell Attorney-Woodhams, Blanchard and Flynn ABSTRACT: A door operator for a canopy-type door including a small driving pinion normally maintained in meshing engagement with an elongated rack member. The driving pinion is preferably rotatably mounted on the door and the elongated rack is preferably pivotally mounted on the adjacent door frame. Resilient means normally maintain the pinion and rack in meshing engagement whereby the driving pinion, being of small diameter, effective functions as a restraining device to hold the door in a stationary position. Manually releasable means are provided for permitting disengagement of the rack and driving pinion to permit manual operation of the door.

ATENIEU JUL 1 319m SHEU 2 OF 3 INVENTOR. dfl/M/ E 14W ff M PATENTED JUL 3191i 3,591. 981

sum 3 [IF 3 INVENTOR. L/W/A B Z A W AIME/WV? DOOR OPERATOR FIELD OF THE INVENTION This invention relates to an automatic operator for counterbalanced canopy-type door and, in particular, relates to an improved operator which automatically functions as a restrain ing device for securely maintaining the door in either an open or closed position, and further including manual release means for permitting manual operation of the door.

BACKGROUND OF THE INVENTION There are many well established advantages of counterbalanced canopy-type closure members, such as garage doors, which advantages include simplicity of installation and operation, easy opening and closing, absence of complicated space consuming support structure normally found in overhung doors, and the automatic weather shield provided by the door when in the open position. However, the present and usual construction of these doors also gives rise to certain problems which, heretofore have not been satisfactorily overcome.

Primary among these problems is the fact that the canopytype door is normally constructed in one piece and thus extends outwardly a substantial distance away from the building upon which it is mounted when in the open position. Since this extension of the door is in a substantially horizontal position when the door is open, adverse weather conditions often cause substantial amounts of snow and ice to collect on the extension, which thus imposes an excessive strain on the structure supporting the door, and also creates a hazard for a person who may be standing under the extension when the door is closed. At least one safety latch, which is shown in U.S. Pat. No. 2,579,621, has been devised for preventing the accidental closure of the open door when it become loaded with snow or ice. However, neither this nor any other latch provides for the elimination of the potential hazard which is created once the latch has been released and the door is free to swing downwardly. Further, such latch devices generally must be manually released and, accordingly, cannot be satisfactorily utilized on canopy-type doors which use motor driven automatic operators since such operators are generally controlled by means of a pushbutton which is installed either inside or outside the garage or are controlled by means of a remote control device positioned within the automobile.

Prior known canopy-type garage doors which have utilized automatic door operators have attempted to overcome the hazards and problems created by snow, ice and wind by using a driving worm in meshing engagement with a driven worm gear for controlling the opening and closing movement of the door. Such worms, when properly designed, are self-locking and thus tend to maintain the door in either the open or closed position. However, as is well know, a worm-worm gear driving arrangement is highly inefficient due to the large sliding friction which exists between the worm and worm gear. Thus, these types of drive door operators have necessitated the use of undesirably large motors.

Further, these prior known door operators have not possessed any convenient release means for permitting disengagement of the drive gears for permitting the door to be manually opened or closed in the event of a power failure.

Accordingly, it is an object of this invention:

1. To provide an improved operator for a movable closure member, particularly a canopy-type garage door.

2. To provide a door operator using a gear and rack drive mechanism for drivably moving the door and for locking the door in a stationary position.

3. To provide a door operator, as aforesaid, wherein a driving pinion of small diameter is utilized for driving the door and for locking same in a stationary position.

4. To provide a door operator, as aforesaid, wherein the driving pinion is normally in meshing engagement with an elongated gear rack which is pivotally mounted on the door frame.

5. To provide a door operator, as aforesaid, including means for easily disengaging the door operator and permitting manual operation of the door. pl 6. To provide a door operator, as aforesaid, including means for permitting disengagement of the driven rack from the driving pinion for permitting manual operation of the door.

7. To provide a door operator, as aforesaid, capable of holding and maintaining the door in the open position even when subjected to snow, ice and wind loads, and for controlling the downward movement of the door when subjected to such loads.

8. To provide a door operator, as aforesaid, which requires less power than prior known door operators.

9. To provide a door operator, as aforesaid, which is economical to manufacture and install and which has increased operating efficiency.

Other objects and purposes of this invention will be apparent to persons acquainted with apparatus of this general type upon reading the following specification and inspecting the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a fragmentary isometric illustration of a garage door having mounted thereon a door operator according to the present invention, the door being shown in the closed positron.

FIG. 2 is a fragmentary isometric view similar to FIG. 1 il- Iustrating the door in the open horizontal position.

FIG. 3 is a fragmentary elevational view illustrating the back side of the door and the door operator mounted thereon, the cover being removed from the power unit to illustrate the details thereof.

FIG. 4 is a side elevational view as take from the right side of FIG. 3.

FIG. 5 is a broken cross-sectional view taken along the line V-V of FIG. 3.

FIG. 6 is a sectional view similar to FIG. 5 and illustrating the rack disengaged from the driving pinion.

FIG. 7 is a partial sectional view taken along the line VII-VII of FIG. 3.

Certain terminology will be used in the following description for convenience in reference only and will not be limiting. The words upwardly, downwardly, rightwardly, and leftwardly ll designate directions in the drawings to which reference is made. The words inwardly" and outwardly" will refer to directions toward and away from, respectively, the geometric center of the device and designated parts thereof. Said terminology will include the words above specifically mentioned, derivatives thereof and words of similar import.

SUMMARY OF THE INVENTION In general, the objects and purposes of the invention are met by providing a door operator for a canopy-type door, which door operator includes a small driving pinion normally maintained in meshing engagement with an elongated rack member. The driving pinion is preferably rotatably mounted on the door and the elongated-rack is preferably pivotally mounted on the adjacent door frame. Resilient means normally maintain the pinion and rack in meshing engagement whereby the driving pinion, being of small diameter, effectively functions as a restraining device to hold the door in a stationary position. Manually releasable means are provided for permitting disengagement of the rack and driving pinion to permit manual operation of the door.

DETAILED DESCRIPTION FIG. 1 illustrates therein a conventional one-piece canopytype door It) in the clo ed vertical position. A door operator according to the present invention, designated generally at 11, is positioned adjacent one of the upper corners of the door. A power unit 12 is mounted on the backside of the door for controlling the door operator II, which in turn controls the opening and closing movement of the door 10.

The door is provided with pivot pins 16 secured thereto and extending outwardly from the opposite sides thereof, each pivot pin 16 being rotatably received within a bearing sleeve 17 (FIG. 4) which is held by means ofa strap member 18 fixed to the door frame 19 and extending longitudinally therealong adjacent one side of the door opening. Since the pivot pins 16 are located more closely adjacent the upper edge of the door than they are the lower edge, the upper portion of the door 10 is provided with a counterbalance compartment 13 which includes any suitable type of counterbalancing weights therein for effectively counterbalancing the door relative to the rotational axis as defined by the pivot pins 16. The abovedescribed door structure and the manner in which same is mounted relative to the frame is conventional and thus will not be described in detail.

The power unit 12 for the operator I1 is preferably mounted directly on the back side of the door substantially adjacent the rotational axis of the door as defined by the pivot pins 16 so as to not effect the balance of the door. The power unit includes a pair of substantially parallel sidewalls 21 and 22 (FIG. 3 which extend outwardly from the back side of the door and are connected by a cover member 23. FIG. 3 illustrates the specific structure of the power unit 12 with the cover member 23 having been removed for purposes of illustration.

In particular, the power unit 12 (FIG. 3 includes a conventional electric motor 26 having a driving pulley 27 fixedly secured to the motor shaft. A flexible endless belt 28 drivingly engages both the driving pulley 27 and a driven pulley 29, the latter being nonrotatably secured to a shaft 30. The shaft 30 rotatably surrounds a further shaft 31 which extends between and is supported by the sidewalls 21 and 22. A conventional clutch plate 32 is nonrotatably secured to the shaft 31 and is positioned substantially adjacent the drive pulley 29. The clutch plate 32 is biased into frictional driving engagement with the pulley 29 by means of a spring 33 which surrounds the end portion of the shaft 31. The other end of the spring 33 bears against a wing nut 36 which is received upon a threaded end portion of the shaft 31. Axial adjustment of the wing nut 36 permits the spring force urging the clutch plate 32 into engagement with the pulley 29 to be selectively adjusted.

The shaft 30 is provided with an intermediate threaded portion 38 on which is threadably engaged a stop member 39. The stop member 39 is guided and nonrotatably restrained by conventional means, such as a slot 40, so as to prevent rotation thereof with the shaft 30. The stop member 39 thus travels axially along the shaft 30 in response to rotation thereof and is adapted to contact one ofa pair of limit switches 41 and 42.

A drive sprocket 43 is fixedly secured adjacent the other end of the inner shaft 31 and is in driving engagement with an endless flexible chain 44. The chain 44 is also in driving en gagement with a driven sprocket 46 nonrotatably secured to a shaft 47, which shaft 47 is rotatably supported within a bearing sleeve 48 fixedly secured to a support plate 49 adjacent the upper' edge of the door. The power unit 12 further includes a relay 34 which permits the initial energization of the motor 26 when the stop member 39 is in contact with one of the limit switches 41 or 42. The power unit 12, as mounted within the cover member 23, constitutes a commercially available power unit and, by itself, does not comprise the present invention.

Rather, the power unit 12 is of significance only in the manner thereunder. The rack 52 is preferably pivo nlly interconnected by means of a pivot pin or bolt 53 to a bracket member 56 which is fixedly secured to the door frame 19 substantially adjacent the upper comer of the door 10. The other end of the rack 52 is provided with an end portion 57 which has threadably engaged therewith and extending therethrough an adjustable stop screw 58.

The rack is maintained in normal meshing engagement with the drive pinion 51 by means of a retaining device 59. The retaining device includes a substantially U-shaped keeper member 61 which has a pair of substantially parallel, upwardly extending leg portions 62 and 63 which are positioned on opposite sides of the rack 52. The keeper member 61 additionally has a base portion 64 which extends between the leg portions 62 and 63 and is displaced downwardly from the rack 52. The leg portions 62 and 63 are provided with aligned openings 66 (FIG. 5) therein through which extends the shaft 47. The keeper member 61 is thus supported on the shaft 47 with the driving pinion 51 being secured to the shaft 47 and positioned between the leg portion 62 and 63 directly above the rack. 52. The keeper member 61 also has a pin 60 supported on and extending between the leg portions 62 and 63, which pin 60 rotatably supports a roller 65 thereon, the roller 65 being positioned substantially adjacent the pinion 51.

The retaining device 59 includes a compression spring 67 for normally maintaining the rack 52 in meshing engagement with the driving pinion 51. One end of the compression ring 67 bears against the base portion 64, whereas the other end of the compression spring bears against a shoe member 68, which shoe member bears against the bottom surface 69 of the rack 52 to maintain same in meshing engagement with the driving pinion 51. The shoe member 68 is provided with a downwardly extending stern portion 71 which passes through the interior of the compression spring 67 and through an opening provided in the base portion 64 so as to extend therebeyond.

As illustrated in FIGS. 4 and 5, the free end of the stem 71 is pivotally connected to a release lever 72 by means of a pivot pin 73. The release lever 72 may be provided with a gripping knob 76 on the free end thereof, the other end of the release lever 72 adjacent the pivot pin 73 being provided with an elongated cam nose 77 thereon adapted to engage the lower surface 78 of the keeper member 61. The compression spring 67 normally maintains the release lever 72 in a substantially horizontal position as illustrated in FIG. 4 whereby the side edge 79 of the release lever abuts the lower surface 78.

As illustrated in FIG. 1, the free end of the release lever 72 may also be connected to one end of an actuating cable 81, the other end of the cable being connected to a conventional key lock lever 82 which is mounted either in the door or in the wall of the building surrounding the door and is accessible from the exterior side of the building and actuatable in a conventional manner by means of a key. The cable 81 and its connection to the key lock lever 82 may be provided as a substitute for or in addition to the gripping knob 76.

OPERATION The operation of the device embodying the invention will be described in detail hereinbelow for a'better understanding of the invention.

In actuating the door operator 11 to move the door 10 from the closed vertical position of FIG. 1 to the open overhead position of FIG. 2, the relay 34 is energized by means of a switch button which is mounted either on the garage or is positioned on a remote control box located within the interior of the automobile. Energization of the relay 34 closes the circuit to the drive motor 26 to permit energization thereof. Drive motor 26, by means of driving pulley 27 and endless belt 28, causes rotation of drive pulley 29 and shaft 30 on which pulley 29 is fixedly secured. Rotation of shaft 30 causes the stop member 39 to linearly move out of contact with the first limit switch 41 whereby the motor 26 thus remains continuously energized when the relay 34 returns to its normally open position. Driving pulley 29, due to its frictional engagement with the spring-urged clutch plate 32, also rotatably drives the inner concentric shaft 31 and the drive sprocket 43 secured to the end thereof. Sprocket 43, through chain 44, thus drives the driven sprocket as fixedly secured to the shaft 47, Pinion 51, being fixed to the shaft 47, and further being in meshing engagement with the rack 52, thus drivingly engages the rack and the reaction between the pinion 51 and the rack 52 causes the pinion 51 to move outwardly (leftwardly in FIG. 4) along the rack so as to swing the door about the pivot pins 16 from the closed vertical position illustrated in FIG. 1 to the open overhead position illustrated in FIG. 2. During this opening movement of the door, the rack 52 is caused to simultaneously pivot downwardly (counterclockwise in FIG. 4) about the axis of the pivot bolt 53 so as to compensate for the singing movement of the door, the rack 52 being maintained in engagement with the pinion 51 by the compression spring 67.

Upon reaching the desired overhead position, the stop member 39 will contact the other limit switch 42 and cause deenergization of the drive motor 26. The door will be maintained in its desired overhead position when the motor is deenergized by means of the meshing engagement between the drive pinion 51 and the elongated rack member 52. Since the drive pinion 51 is ofa smaller diameter, it cooperates with the rack 52 to substantially function as a locking or restraining means. In fact, it has been discovered that the use of such a small diameter pinion effectively maintains the door in the open overhead position even when the door is subjected to heavy snow, ice and wind loads.

The pinion 51 and its cooperation with the rack 52 is effective to maintain the door stationary in any selected position due to the power unit 12 containing therein a power transmission train connecting the drive motor 26 to the pinion 51 for causing a substantial speed reduction, which in turn results in a substantially large mechanical advantage in the normal direction of torque transmission from the motor 26 to the pinion 51. Consequently, any tendency for external loads to move the door 10 and cause rotation of the pinion 51 is effectively restrained or prevented since the large mechanical advantage from the motor to the pinion effectively resists any tendency for the small diameter pinion to rotatably drive the motor. Thus, the external forces impose a driving torque on the pinion which is unable to overcome the frictional and inertia forces present in the transmission means which, when am plified by the mechanical advantage of the power unit, effectively prevent movement of the door.

In one embodiment of the present invention, the pinion 51 was formed integral with the shaft 47, the pinion being machined from one end of the shaft with the shaft originally having an external diameter of approximately three-fourths inch. Thus, it has been experimentally determined that door operators constructed according to the present invention are effective in restraining and preventing any undesired movement of the door when the drive pinion 51 has a diameter of about three-fourths inch. However, it will be recognized that the diameter can be varied somewhat in relation to the specific power unit 12 utilized, since the amount of friction, inertia and mechanical advantage of the power unit will represent variable factors which will permit the use of various sizes of small diameter pinions.

In the event that the limit switch 42 is not properly positioned so as to be contacted by the stop 39 when the door reaches the desired overhead position, then the roller 65 will contact the adjustable stop screw 58 to prevent any further movement of the door and likewise prevent any additional rotation of the pinion 51. Thus, since pinion 51 is prevented from rotating, the concentric shaft 31 interconnected to the pinion 51 by means of the drive chain 44 is also prevented from rotating, whereupon the clutch plate 32 remains stationary and thus slips relative to the drive pulley 29. However, since motor 26 is still energized, it will continue to rotate and likewise the drive pulley 29 and its associated shaft 30 will continue to rotate until the stop member 3& linearly moves into contact with the limit switch 42 so as to deenergize the motor 26.

When it is desired to close the door 10, the relay 34 is again energized, which in turn causes energization of the drive motor as, which motor now drives in the reverse direction. The pinion ER is thus rotated in the opposite direction and, due to its meshing engagement with the rack 52, causes the door It) to be moved downwardly to the closed vertical position whereupon the door operator again assumes its original position substantially as illustrated in FIGS. 3 and 4, the motor 26 again being deenergized after the top 39 has moved linearly back to its original position in contact with the limit switch 41.

The small diameter pinion 51 and its normal engagement wit the rack 52 effectively functions as a locking means for maintaining the door stationary when the door is in its opened or closed position. Thus, any attempt to manually open or close the door when the pinion 51 is in meshing engagement with the rack 52 will not be possible. However, since various types of power failures often occur, such as a temporary loss of electrical power, or a failure within the power unit 12, such as a failure of the drive motor 26, it is necessary to be able to manually operate the door 10 so as to have access to and from the garage or building. Accordingly, the present invention provides the retaining device 59 for normally maintaining meshing engagement between the pinion 51 and the rack 52, which retaining device can be manually released to cause the rack 52 to move out of meshing engagement with the drive pinion 51, whereupon the door. 10 can then be manually pivoted so as to either open or close same.

To disengage the rack 52 from the pinion 51, the release lever 72 is pivoted downwardly (counterclockwise in FIGS. 4 and 5) about the pivot pin 73, which pivotal movement causes the elongated cam nose 77 to contact the lower surface 78 of the keeper member 61. The elongated cam nose 77, as it is pivoted into engagement with the surface 78, causes the pivot pin 73 to move downwardly away from the surface 78, which in turn exerts a downward force on the stem 71 whereupon the stem 7E and the shoe member 68 are likewise moved downwardly in opposition to the compression spring 67. As the shoe 68 is moved downwardly toward the base portion 64 of the keeper member 61, the rack 52, due to its own weight, likewise swings downwardly (counterclockwise in FIG. 4 and 5) about the pivot bolt 53 so as to move out of meshing engagement with the driving pinion 51 (FIG. 6). When the release lever has been swung approximately into a substantially vertical position, the flat portion 83 formed on the end of the cam nose will engage the lower surface 78 so that the release lever will then be normally maintained in the released vertical position (FIG. 6) to permit manual operation of the door. The rack 52 can obviously be returned to its normal meshing engagement with the pinion 51 by manually swinging (clockwise in FIG. 6) the release lever 72 back to the normal horizontal position illustrated in FIGS. 4 and 5.

The lever 72 can be manually released from the interior of the garage, as by gripping the knob 76 or by pulling downwardly on the cable 81. Alternatively, the release lever 72 can be actuated exteriorly of the garage by means of the key lock lever 82, whereby actuation of the key lock lever 82 by means of a key will in a conventional manner cause rotation of the lever 82, which in turn will exert a downward pull on the cable 81 so as to move the lever 72 to the vertical released position. This latter feature is especially advantageous in the event of a power failure since it permits the garage door to be manually operated entirely from the exterior side thereof.

When rack 52 is disengaged from pinion 51 to permit manual operation of the door, the upward opening movement of the door is limited by the roller 65 contacting the end of the stop screw 58. The longitudinal axis of the stop screw 58 and the rotational axes of the roller 65 and pinion 51 and preferably positioned substantially. within a single plane so than contact between stop screw 58 and roller 65 will not tend to dislodge the retaining device 59 from its released position.

While the invention is disclosed as utilizing a shoe member 68 biased into abutting engagement with the bottom surface of the rack 52 for permitting compression of the spring 67 so as to permit the rack 52 to be released from the driving pinion 51, it will be apparent that the shoe member 68 could be eliminated ifdesired and the stem 71 extended so as to be pivotally connected directly to the rack 52. Further, numerous other types of linkages could be connected either directly or indirectly to the rack 52 for pivotally moving same out of engagement with the driving pinion 51 in opposition to the spring 67.

lt will be apparent that the present invention thus relates to an operator which permits a canopy-type door to be simply and conveniently automatically operated with the operator further functioning as a lock device for maintaining the door in either the open or closed position, which lock device is able to withstand heavy loads such as imposed on the door by wind, snow and ice. Further, the invention permits the automatic lock device incorporated within the operator to be easily released, either from the interior or the exterior of the building, to permit manual operation of the door when desired.

lclaim:

1. An operator for a movable closure structure which is positionable within an opening in an upright wall, the closure structure being pivotally connected to said wall for vertical movement between a substantially vertical position in which said closure structure closes said opening and a substantially horizontal overhead position, comprising:

a driving pinion and means rotatably mounting said pinion on said movable closure structure adjacent one edge thereof;

an elongated substantially rigid gear rack and means pivotally mounting said gear rack on said upright wall substantially adjacent the one edge of said closure structure;

retaining means normally maintaining said pinion and said gear rack in meshing engagement with one another;

drive means interconnected to said pinion for rotating same and for causing driving engagement with said rack to cause swinging movement of said closure structure between said overhead and said closed positions; and

release means for causing relative movement between said driving pinion and said gear rack in a direction away from one another to cause said pinion and rack to be meshingly disengaged from one another for permitting manual operation of said closure structure.

2. An operator according to claim 1, wherein said driving pinion is of substantially small diameter and said elongated gear rack is substantially straight and is pivotally connected at one end thereof to said upright wall, the other end of said gear rack being substantially free.

3. An operator according to claim 2, wherein said driving pinion is a small diameter spur gear, and wherein said drive means includes a motor mounted on said closure structure and transmission means connected between said motor and said pinion for driving same.

4. An operator according to claim 2, wherein said retaining means includes resilient means for normally maintaining said gear rack in engagement with said pinion, and wherein said release means coacts with said rack for moving the rack in opposition to said resilient means away from said pinion to meshingly disengage the rack from the pinion.

5. An operator according to claim 3, wherein said transmission means provides a substantially large mechanical advantage from said motor to said pinion for effectively locking said closure structure and preventing movement thereof due to imposition of external forces onto said closure structure, said transmission means including only nonlocking gear connections therein.

6. An operator according to claim ll, wherein said closure structure comprises a one-piece counterbalanced door mounted for vertical pivot movement about an axis disposed downwardly a substantial distance from the upper edge of said door.

7. An operator for a movable closure structure which is positioned within an opening in an upright wall, the closure structure being pivotally connected to said wall for movement between a substantially vertical position in which said closure structure closes said opening and a substantially horizontal overhead position, comprising:

a driving pinion and means rotatably mounting said pinion on said movable closure structure adjacent one edge thereof, said lastmentioned means including a pinion shaft rotatably mounted on said closure structure with said driving pinion being fixedly secured to said pinion shaft;

an elongated, substantially rigid gear rack and means pivotally mounting said gear rack on said upright wall substantially adjacent the one edge of said closure structure;

retaining means normally maintaining said pinion and said gear rack in meshing engagement with one another, said retaining means including a keeper member rotatably supported on said pinion shaft and spring means coacting between said keeper member and said gear rack for urging same into meshing engagement with the driving pinion;

release means coacting with said gear rack for permitting same to pivotally move in opposition to said spring means out of engagement with said pinion; and

drive means interconnected to said pinion for rotating same and for causing driving engagement with said rack to cause swinging movement of said closure structure between said overhead and said closed positions.

8. An operator according to claim 7, wherein said release means further includes means for maintaining said gear rack in said released position out of engagement with said pinion for permitting manual operation of said closure structure.

9. In combination with a one-piece door which is positionable within an opening in an upright wall means, the door being pivotally connected to said wall means for vertical swinging movement between a substantially vertical position in which said door closes said opening and a substantially horizontal overhead open position, and an operator for pivotally moving said door between said positions, the improvement wherein said operator comprises:

pinion means rotatably mounted on one of said door and said upright wall means, said pinion being disposed adjacent the upper edge of the opening formed in said upright wall means when said door is in said vertical position;

an elongated substantially rigid gear rack and connecting means pivotally connecting said rack to the other of said door and said upright wall means, said connecting means also being disposed adjacent the upper edge of said opening when the door is in the vertical position;

engagement means for normally maintaining said pinion means and said gear rack in meshing engagement with one another;

drive means interconnected to said pinion means for rotating same and for causing driving engagement with said rack for causing tilting movement of said door between said open and said closed positions; and

release means coacting between said rack and said pinion means for permitting said rack and said pinion means to be meshingly disengaged to enable said door to be manually tilted between said positions.

10. The combination according to claim 9, wherein said drive means includes motor means and torque transmitting means connected between said motor means and said pinion means, said torque transmitting means including only nonlocking gear connections therein while having a substantially large mechanical advantage from said motor means to said pinion means for effectively preventing rotation of said motor means by said pinion means due to imposition of external forces on said door.

II. The combination according to claim 9, wherein said pinion means is rotatably mounted on said door adjacent an upper corner thereof, and said gear rack being pivotally connected to said upright wall means adjacent the upper edge of rack for pivotally urging same into meshing engagement with said pinion means, and said release means coacting with said rack for permitting same to pivotally move away from and out of meshing engagement with said pinion means in opposition to said spring means. 

1. An operator for a movable closure structure which is positionable within an opening in an upright wall, the closure structure being pivotally connected to said wall for vertical movement between a substantially vertical position in which said closure structure closes said opening and a substantially horizontal overhead position, comprising: a driving pinion and means rotatably mounting said pinion on said movable closure structure adjacent one edge thereof; an elongated substantially rigid gear rack and means pivotally mounting said gear rack on said upright wall substantially adjacent the one edge of said closure structure; retaining means normally maintaining said pinion and said gear rack in meshing engagement with one another; drive means interconnected to said pinion for rotating same and for causing driving engagement with said rack to cause swinging movement of said closure structure between said overhead and said closed positions; and releAse means for causing relative movement between said driving pinion and said gear rack in a direction away from one another to cause said pinion and rack to be meshingly disengaged from one another for permitting manual operation of said closure structure.
 2. An operator according to claim 1, wherein said driving pinion is of substantially small diameter and said elongated gear rack is substantially straight and is pivotally connected at one end thereof to said upright wall, the other end of said gear rack being substantially free.
 3. An operator according to claim 2, wherein said driving pinion is a small diameter spur gear, and wherein said drive means includes a motor mounted on said closure structure and transmission means connected between said motor and said pinion for driving same.
 4. An operator according to claim 2, wherein said retaining means includes resilient means for normally maintaining said gear rack in engagement with said pinion, and wherein said release means coacts with said rack for moving the rack in opposition to said resilient means away from said pinion to meshingly disengage the rack from the pinion.
 5. An operator according to claim 3, wherein said transmission means provides a substantially large mechanical advantage from said motor to said pinion for effectively locking said closure structure and preventing movement thereof due to imposition of external forces onto said closure structure, said transmission means including only nonlocking gear connections therein.
 6. An operator according to claim 1, wherein said closure structure comprises a one-piece counterbalanced door mounted for vertical pivot movement about an axis disposed downwardly a substantial distance from the upper edge of said door.
 7. An operator for a movable closure structure which is positioned within an opening in an upright wall, the closure structure being pivotally connected to said wall for movement between a substantially vertical position in which said closure structure closes said opening and a substantially horizontal overhead position, comprising: a driving pinion and means rotatably mounting said pinion on said movable closure structure adjacent one edge thereof, said last-mentioned means including a pinion shaft rotatably mounted on said closure structure with said driving pinion being fixedly secured to said pinion shaft; an elongated, substantially rigid gear rack and means pivotally mounting said gear rack on said upright wall substantially adjacent the one edge of said closure structure; retaining means normally maintaining said pinion and said gear rack in meshing engagement with one another, said retaining means including a keeper member rotatably supported on said pinion shaft and spring means coacting between said keeper member and said gear rack for urging same into meshing engagement with the driving pinion; release means coacting with said gear rack for permitting same to pivotally move in opposition to said spring means out of engagement with said pinion; and drive means interconnected to said pinion for rotating same and for causing driving engagement with said rack to cause swinging movement of said closure structure between said overhead and said closed positions.
 8. An operator according to claim 7, wherein said release means further includes means for maintaining said gear rack in said released position out of engagement with said pinion for permitting manual operation of said closure structure.
 9. In combination with a one-piece door which is positionable within an opening in an upright wall means, the door being pivotally connected to said wall means for vertical swinging movement between a substantially vertical position in which said door closes said opening and a substantially horizontal overhead open position, and an operator for pivotally moving said door between said positions, the improvement wherein said operator comprises: pinion means rotatably mountEd on one of said door and said upright wall means, said pinion being disposed adjacent the upper edge of the opening formed in said upright wall means when said door is in said vertical position; an elongated substantially rigid gear rack and connecting means pivotally connecting said rack to the other of said door and said upright wall means, said connecting means also being disposed adjacent the upper edge of said opening when the door is in the vertical position; engagement means for normally maintaining said pinion means and said gear rack in meshing engagement with one another; drive means interconnected to said pinion means for rotating same and for causing driving engagement with said rack for causing tilting movement of said door between said open and said closed positions; and release means coacting between said rack and said pinion means for permitting said rack and said pinion means to be meshingly disengaged to enable said door to be manually tilted between said positions.
 10. The combination according to claim 9, wherein said drive means includes motor means and torque transmitting means connected between said motor means and said pinion means, said torque transmitting means including only nonlocking gear connections therein while having a substantially large mechanical advantage from said motor means to said pinion means for effectively preventing rotation of said motor means by said pinion means due to imposition of external forces on said door.
 11. The combination according to claim 9, wherein said pinion means is rotatably mounted on said door adjacent an upper corner thereof, and said gear rack being pivotally connected to said upright wall means adjacent the upper edge of said opening, said rack being positioned for meshing engagement with said pinion means adjacent the lower side thereof whereby the weight of said rack tends to swing said rack downwardly out of meshing engagement with said pinion means.
 12. The combination according to claim 9, wherein said engagement means includes spring means coacting against said rack for pivotally urging same into meshing engagement with said pinion means, and said release means coacting with said rack for permitting same to pivotally move away from and out of meshing engagement with said pinion means in opposition to said spring means. 